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Java - replace first 3 characters in string
3 points
In this article, we would like to show you how to replace the first 3 characters in string in Java.
Quick solution:
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String text = "ABCD";2
String replacement = "xyz";3
String result = replacement + text.substring(3);4
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System.out.println(result); // xyzDor:
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String text = "ABCD";2
String replacement = "xyz";3
String result = replacement.concat(text.substring(3));4
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System.out.println(result); // xyzDor:
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String text = "ABCD";2
String replacement = "xyz";3
String result = text.replaceAll("^.{3}", replacement);4
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System.out.println(result); // xyzD
In this example, we remove last 3 characters from the original string and add the replacement at the beginning.
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public class Example {2
3
public static void main(String[] args) {4
String text = "ABCD";5
String replacement = "xyz";6
String result = replacement + text.substring(3);7
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System.out.println(result); // xyzD9
}10
}This approach is equivalent to the above one. Instead of + operator we concatenate the strings using concat() method.
xxxxxxxxxx1
public class Example {2
3
public static void main(String[] args) {4
String text = "ABCD";5
String replacement = "xyz";6
String result = replacement.concat(text.substring(3));7
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System.out.println(result); // xyzD9
}10
}In this example, we use string replaceAll() with "^.{3}" regex to replace the first 3 characters in the text string.
Regex explanation:
^- matches the beginning of the string,.- matches any character except linebreaks,{3}- matches the specified quantity of the previous token (in our case the.).
xxxxxxxxxx1
public class Example {2
3
public static void main(String[] args) {4
String text = "ABCD";5
String replacement = "xyz";6
String result = text.replaceAll("^.{3}", replacement);7
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System.out.println(result); // xyzD9
}10
}Note:
Regular expressions are slower than
substring()method.
